Expansive use of smart devices with audio input/output capability, e.g., speech recognition, voice communication, etc., has increased the need to improve audio quality. The quality of recorded speech signals from a desired talker of interest may be adversely affected by the presence of interfering signals such as noise and echo. For example, sound from a loudspeaker may reflect back to a microphone, producing an echo. As a result, audio devices may include acoustic echo cancelers (AECs), for reducing such echoes. AECs exploit knowledge of the loudspeaker playback signal to cancel the echo in the microphone recording. In some systems, echo may be controlled and reduced with a reference loudspeaker playback signal that cancels the echo on each input channel (e.g., microphone input signals) by reducing the power of the echo signal at the processed output using linear filtering.
Unfortunately, most audio transducers, e.g., microphones, loudspeakers, power amplifiers, etc., are nonlinear, resulting in reduced performance of linear AECs. For example, small loudspeakers and poorly designed enclosures may lead to nonlinear echoes that are not addressed by traditional AECs. As such, these systems are not suited for reducing nonlinear echo signals. In some conventional echo and noise reduction systems, a set of AECs may be utilized to reduce echo signals at the input to a beamformer, and the beamformer is used to reduce noise. Unfortunately, any additional (residual) echo is not canceled by the beamformer, because the beamformer is used to reduce noise and not echo.